var h = 0, v = 1;
var r = parseInt(f.style.right) - h;
var b = parseInt(f.style.bottom) - v;

if (b > -210) {
	v += 2;
} else {
	h = (v > 9) ? v * 0.2 : 0;
	v *= (v > 9) ? -0.6 : 0;
	if(v == 0){
		clearInterval(i);
	}
}

	
最好用chrome观看demo,你懂的...
By 写点寂寞 @Author:Fzxa
FPS: